         ))
 
 (def my-code-url "https://github.com/pauldoo/scratch/blob/master/ClojureScript/hello.cljs")
-(def tick-step (/ 1 100))
+(def tick-step (/ 1 200))
 (def render-step (/ 1 30))
-(def gravity-strength 15)
-(def ground-strength 10)
+(def gravity-strength 500)
+(def ground-strength 200)
 (def initial-game-state {
     :nodes {
         :t {
             :pos [150 100]
-            :vel [(- 10) 0]
+            :vel [0 0]
         }
         :u {
             :pos [350 200]
-            :vel [(- 10) 0]
+            :vel [0 0]
         }
         :v {
             :pos [250 100]
-            :vel [(- 10) 0]
+            :vel [0 0]
         }
     }
     :springs [

            :node-a :t
            :node-b :u
            :rest-length 224.0
            :strength 50
        }
        {
            :node-a :u
            :node-b :v
            :rest-length 141.0
            :strength 50
        }
        {
            :node-a :t
            :node-b :v
            :rest-length 100.0
            :strength 50
        }
    ] })


    (zipmap (keys nodes)
        (map (fn [{[ x y ] :pos [ xv yv ] :vel }]
            (if (< y 0)
                (vec* [(- xv) (+ (Math/max 0 (- yv)) (- y))] ground-strength)
                [0 0])) (vals nodes))))

(defn calculate-all-node-forces [nodes springs]
